1. Field of the Invention
The present invention relates to a method of controlling a terminal crimping device which produces terminal-equipped cables constituting a wire harness or the like.
2. Description of the Prior Art
The terminal crimping device is, in general, composed of a crimper and an anvil set opposite to said crimper wherein the crimper performs the work of crimping terminals to the exposed conductors of the cables through elevating actions thereof. In this connection, the Japanese Patent Appln. No. 6-328827 discloses that the elevating actions are achieved by decelerating the rotation of the servo motor before being transmitted to a disk where the disk rotation is converted into a linear motion such that a ram loaded with said crimper is elevated and lowered. A detailed explanation thereof will be given with reference to FIGS. 10A and 10B and FIG. 11.
FIGS. 9A through 9C are figures explaining the action of the terminal crimping device; FIG. 10A is a graph showing the relationship between the crimper action time and the elevating speed; and FIG. 10B is a graph showing the relationship between the time and the motor current value wherein 1, 2, 3, in FIGS. 10A and 11B correspond to A, B and C in FIG. 9.
Referring to FIG. 9, the disk 7 is secured to the output shaft of the decelerator (not shown), which functions to decelerate the rotation of the servo motor.
The disk 7 secured at an axis thereof to the output shaft of the decelerator carries all eccentric pin (crank shaft) 8 thereon. A crank rod 9 pivotally attached at an upper end thereof to said eccentric pin 8 while said crank rod 9 is pivotally attached at a lower end thereof to a ram 11. Said ram 11 is loaded slidably in a vertical direction within a ram guide which is provided within the inner surfaces of a frame (not shown). In this way, the disk 7, the crank rod 9, the ram 11 and the ram guide constitute a piston/crank mechanism.
The ram 11 is formed at a lower end thereof an engagement recess 13, which is removably loaded with an engagement head 16 of a crimper holder 15 carrying a crimper 14. Immediately beneath said crimper 14, an anvil 17 is secured to a base 2 positioned opposite to said crimper 14.
FIG. 9A shows the start of the crimping step in which the crank pin 8 of the disk 7 takes an uppermost position to place the crimper 14 in the top dead center, when the descending speed of the crimper 14 stands at 0 while the load current stands at 0 as shown in FIG. 10A.
FIG. 9B shows a rotation of the disk 7 in the arrow-marked direction which causes the eccentric pin 3 to move downward until the crimper 14 reaches a position in its high speed descent to contact the barrel c of a terminal, thus starting a crimping action therefor. The descending speed of said crimper 14 is reduced before the contact thereof while reducing the load current.
FIG. 9C shows that the disk 7 rotates in the arrow-marked direction to move the eccentric pin 8 to the neighborhood of the bottom dead center such that the crimper 14 and the anvil 17 substantially performs the crimping work and, then, the crimper 14 provisionally comes to a stop at the crimpinq position. At this time, the crimper 14 is at rest (stop time t) showing a speed 0 while maintaining the state of pressurizing and pinching the barrel c of the terminal to continue the pressurizing action against the springback of the terminal barrel c, thus the load current reaching the peak value while showing a rising curve. Springback of said barrel c is prevented through this pressurizing and pinching action by this provisional halt.
After the terminal crimping, the servo motor 4 is caused to rotate the disk 7 in a direction reverse to the arrow-marked direction in the state shown in FIG. 9C such that the crimper 14 ascends to restore to the state A.
In FIGS. 10A and 10B, the descending speed of the crimper 14 is sufficiently reduced from the speed thereof shown during the descent from the uppermost position to the terminal crimping start position. Therefore, such impact noise as caused in a conventional flywheel type terminal crimping device will not be generated, thus contributing to noise prevention and job site improvement.
The determination whether the terminal crimping performance is good or not has been done by recording as shown in FIG. 11 the reference values of crimping torques (motor drive electric current) to the time for terminal press attaching (between (iii) and (iv) of FIG. 10B and the reference values of the outputs from the height sensor to the time; comparing the actual torque required in crimping operation and the output value of the height sensor with the reference values; and determining the performance as being good if within the prescribed value ranges and as being not good if out of the same.
As set forth in the foregoing description, the determination whether the terminal crimping performance is good or not has been done by conducting the comparison with the reference values to the recorded time as mentioned in the foregoing description. Therefore, any fluctuation in the motor rotation can create a different reference value to cause an error in the determination result.